A police officer stands in front of Amesbury Baptist Church, which has been cordoned off after two people were hospitalised and police declared a 'major incident', in Amesbury, Wiltshire, Britain, July 4, 2018. REUTERS/Henry Nicholls

LONDON (Reuters) - The case of two people whose possible poisoning is being investigated by counter-terrorism police is being treated with the “utmost seriousness”, a spokesman for Prime Minister Theresa May said on Wednesday.

The British government’s emergency response committee had met over the incident in Wiltshire, southwest England, and ministers were being regularly updated.

“This is an incident which understandably is being treated with the utmost seriousness,” the spokesman said. “Ministers and the prime minister are being kept regularly updated and there was a meeting this morning of officials to receive updates on the facts and the situation on the ground.”

The pair were found in critical condition from suspected exposure to an unknown substance near the English city of Salisbury where a former Russian spy was poisoned in March.

Reporting By William James. Writing by Andrew MacAskill; editing by Stephen Addison